The invention relates to a filter or catalyst body for removing harmful constituents from the waste gases of an internal combustion engine, especially a diesel engine, comprising at least one fabric layer of metal wires or metal fibres, sintering material in the form of powder, granules, fibre fragments or chips being introduced into the meshes and being sintered on to the wires or fibres.
A filter or catalyst body of this kind is described, e.g. in DE-A 39 08 581.
In this case, a multilayer woven or knitted fabric is used as the base material, wires or fibres being placed flat on top of one another in several layers.
One main sphere of application of a body of this kind is internal combustion engines in motor vehicles, ecologically harmful and/or noxious constituents such as soot, carbon monoxide, hydrocarbons and nitrogen oxides being removed from the waste gas flow.
However, the economical and practical application of filter or catalyst bodies of this kind has not been possible hitherto as a result of the problems encountered in this sphere.
One disadvantage, e.g. is the fact that filter or catalyst bodies are in themselves relatively inhomogeneous, this being particularly true of an irregularly formed knitted fabric. Similarly, the transmission of heat to the body and the thermal conductivity therein is limited. Therefore, the heat cannot always be dissipated in a uniform manner, and there is a risk of local overheating, so that uniform soot combustion cannot be guaranteed. A further problem with the known filter bodies consists in that they have limited mechanical stability. This would lead to problems when used in the waste gas flow of an internal combustion engine as a result of the rough loading occurring in this connection, especially high temperatures and pressure pulsations, so that filter or catalyst bodies of the type described hereinbefore cannot yet be used economically for this sphere of application.